Magnetic recording media in which magnetic recording layers containing magnetic powders are formed on non-magnetic supports have hitherto been provided with backcoat layers on surfaces of the non-magnetic supports opposite to the magnetic layers, for improving the running properties of the media themselves. Although such backcoat layers contribute to improvements in running characteristics, formation of the backcoat layers itself requires further coating and drying aside from formation of the magnetic layers, resulting in complicated manufacturing processes to directly affect the production cost. Adoption thereof are therefore limited to high-grade products.
On the other hand, recent magnetic recording media have increased in demands for enhanced manufacturing efficiency, and it has been strongly desired to improve coating processes.
For satisfying such demands, the following techniques in respect to the amount of the paint coated have been proposed.
That is to say, methods for producing a magnetic recording medium are proposed in which when two-layer coating is carried out on one side of a non-magnetic support, the amount of a coating solution coated in each layer is specified. Such methods include "a coating method of a magnetic recording medium comprising previously coating a running support with a first coating solution, and coating it with a second coating solution by pressing an extrusion nozzle of a coating head for the second coating solution onto a coated surface of said first coating solution without supporting a back side of said support, while said first coating solution is not dried yet, in which the amount of the first coating solution coated is 60 cc/m.sup.2 or less, and the amount of the second coating solution coated is 50 cc/m.sup.2 or less" (Japanese Examined Patent Publication No. 5-59491) and "a method for producing a magnetic recording medium comprising forming a plurality of magnetic layers on a running flexible support by sequential or simultaneous coating in multiple layers in a wet state, followed by drying and calendering, in which (a) at least an urethane resin is added to a binder for a paint of the lower magnetic layer and the amount thereof coated is controlled to 30 cm.sup.3 /m.sup.2 or less, and (b) a vinyl chloride resin and an urethane resin each containing a polar group are added to a binder for a paint of the uppermost layer, a mixture is kneaded at an actual load of a motor applied in kneading of at least 0.1 kW/kg of magnetic powder for 5 minutes to 2 hours, and the amount thereof coated is controlled to 25 cm.sup.3 /m.sup.2 " (Japanese Unexamined Patent Publication No. 3-120618).
Further, methods for producing a magnetic recording medium are proposed in which a coating solution for a magnetic layer and a coating solution for a backcoat layer are applied, and then, both the coating films are simultaneously dried, for reducing a coated sheet loss. Such methods include "a method for producing a magnetic recording medium having a magnetic layer formed on one side of a non-magnetic support and a backcoat layer formed on the other side of the non-magnetic support, which comprises the steps of coating one side of the non-magnetic support with a magnetic paint for formation of the magnetic layer, coating the other side of the non-magnetic support with a paint for formation of the backcoat layer, and applying a magnetic field thereto after application of said magnetic paint for formation of the magnetic layer and said paint for formation of the backcoat layer while the magnetic paint for formation of the magnetic layer is not dried yet to conduct magnetic field orientation treatment, wherein when the magnetic paint for formation of the magnetic layer and the paint for formation of the backcoat layer are applied, both the paints keep undried" (Japanese Unexamined Patent Publication No. 9-185822).
However, in the proposals described in Japanese Examined Patent Publication No. 5-59491 and Japanese Unexamined Patent Publication No. 3-120618 mentioned above, the amount of the paint coated on the backcoat layer side is not described, and it can not be said that measures in respect to the appearance of coated sheet rolls after winding are sufficient.
Further, in the proposal described in Japanese Unexamined Patent Publication No. 9-185822, the method for producing the magnetic recording medium is described in which both the coating films of the magnetic layer and the backcoat layer are simultaneously dried for reducing the production cost. However, the amounts coated for the magnetic layer and the backcoat layer are not specified, and no measures are taken with respect to the appearance of a coated sheet roll after winding.